1. Field of the Invention
The present invention relates to safety apparatus for restraining the head and body of the occupant of a vehicle to reduce the extent and severity of injuries during a crash of the vehicle. More specifically, it relates to an inflatable air bag system attached to the occupant's safety belts that removes any slack in the safety belts, distributes crash loads over a larger area, and provides chin support to reduce head and neck movement upon impact.
2. Background of the Invention
Conventional safety belts are designed to protect the occupants of vehicles such as automobiles, airplanes, helicopters, trains, trucks, boats and ships from primary injuries during an accident. Primary injuries are injuries caused by the initial impact of the occupants against the interior of the vehicle. However, the protection provided by conventional safety belts against even primary injuries may be inadequate. For example, slack safety belts may lead to unnecessarily serious primary injuries. Moreover, the safety belts themselves may often be responsible for secondary injuries. Secondary injuries are injuries caused by the restraint system, or by the body as it recoils after the initial impact. For example, if the load from the safety belts is directed over small areas of the occupant's body, the safety belts themselves may cause serious injuries. Finally, even if a restraint system successfully prevents the displacement of the occupant's torso, displacement of the head may still occur, resulting in neck and/or chest injuries.
U.S. Pat. Nos. 3,948,541 and 3,905,615 to M. Schulman, disclose an inflatable body and head restraint system, wherein a bladder member is securely affixed to shoulder straps and a lap belt. The bladder member has chin, chest and pelvic bags. Upon impact, the bladder member automatically inflates to cushion the pelvic and chest areas and to prevent forward rotation of the head.
These systems suffer from a series of severe drawbacks. First, upon inflation the bladder tends to roll out from its position under the shoulder straps, as shown in FIGS. 1a-1c. Since the bladder is stowed under the harness, it is not fully deployed before the load is applied to the straps. In a crash, there is significant load on the strap, preventing the underlying bag from lifting the strap uniformly away from the occupant. Instead, the bag tends to deploy in the direction of least resistance, so that it rolls out to one side of the strap.
Second, the seams and the webbing of the air bag tend to split during inflation. Upon impact, the harness exerts great force against the occupant's body. Because the bladders are underneath the straps, part of the bladder is constricted by the harness, resulting in high pressure in the other parts of the bladder. The abnormally high pressure in these portions of the bladder leads to seam and web splitting and, consequently, to failure of the bladder system.
Third, the gas generator used to inflate the bladders in the Schulman system is located in the lap belt, interfering with access to the lap belt and causing pelvic pain upon impact.
Finally, the chest bag allows too much rotation of the head and neck. The location of the gas generator under the lap belt has also caused structural failure of the lap belt buckle.
Simple inflatable body restraints are also disclosed in U.S. Pat. No. 3,682,498 to W. Rutzki and U.S. Pat. No. 4,348,037 to B. Law et al. Both patents disclose inflatable protective devices that are located in or under the safety harnesses to which they are attached. As described above, these inflatable devices are subject to rollout and seam or web splitting or inadequate occupant protection when inflate.